The Mercury Photosensitized Decomposition of the Deuteroammonias

A method of preparation of ammonias in which one, two and three hydrogens are replaced by deuterium has been devised. It reveals that the preparation of magnesium nitride from magnesium and ammonia yields amido- or imido-compounds as intermediate stages of great stability. The physical properties of deuteroammonia preparations have been studied. Ultraviolet absorption spectra reveal the presence of all three substituted deuteroammonias in the preparations studied. The mercury photosensitized decomposition of trideuteroammonia is more than ten times slower than the corresponding reaction of ammonia. It is also inhibited much more strongly by deuterium than is ammonia decomposition by hydrogen. Increasing deuterium content of ammonia decreases the rate of sensitized decomposition. The kinetics of decomposition are qualitatively similar but quantitatively different. The quantitative results are compared with data on quenching of fluorescence of mercury resonance radiation by the several gases in question and lead to important conclusions concerning the nature of the collisions involved in the decomposition process.